title: Bacterial enzymes for dissimilatory sulfate reduction in a marine microbial mat (Black Sea) mediating anaerobic oxidation of methane.
abstract: Anaerobic oxidation of methane (AOM) with sulfate is catalysed by microbial consortia of archaea and bacteria affiliating with methanogens and sulfate-reducing Deltaproteobacteria respectively. There is evidence that methane oxidation is catalysed by enzymes related to those in methanogenesis, but the enzymes for sulfate reduction coupled to AOM have not been examined. We collected microbial mats with high AOM activity from a methane seep in the Black Sea. The mats consisted mainly of archaea of the ANME-2 group and bacteria of the Desulfosarcina-Desulfococcus group. Cell-free mat extract contained activities of enzymes involved in sulfate reduction to sulfide: ATP sulfurylase (adenylyl : sulfate transferase; Sat), APS reductase (Apr) and dissimilatory sulfite reductase (Dsr). We partially purified the enzymes by anion-exchange chromatography. The amounts obtained indicated that the enzymes are abundant in the mat, with Sat accounting for 2% of the soluble mat protein. N-terminal amino acid sequences of purified proteins suggested similarities to the corresponding enzymes of known species of sulfate-reducing bacteria. The deduced amino acid sequence of PCR-amplified genes of the Apr subunits is similar to that of Apr of the Desulfosarcina/Desulfococcus group. These results indicate that the major enzymes involved in sulfate reduction in the Back Sea microbial mats are of bacterial origin, most likely originating from the bacterial partner in the consortium.
authors.affiliation: Max Planck Institute for Marine Microbiology, Bremen, Germany.
authors.forename: Mirko
authors.initials: M
authors.lastname: Basen
authors.forename: Martin
authors.initials: M
authors.lastname: Krüger
authors.forename: Jana
authors.initials: J
authors.lastname: Milucka
authors.forename: Jan
authors.initials: J
authors.lastname: Kuever
authors.forename: Jörg
authors.initials: J
authors.lastname: Kahnt
authors.forename: Olav
authors.initials: O
authors.lastname: Grundmann
authors.forename: Anke
authors.initials: A
authors.lastname: Meyerdierks
authors.forename: Friedrich
authors.initials: F
authors.lastname: Widdel
authors.forename: Seigo
authors.initials: S
authors.lastname: Shima
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism; D059038:Black Sea; D020564:Deltaproteobacteria / Q000145:classification / Q000201:enzymology; D050885:Hydrogensulfite Reductase / Q000302:isolation & purification / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000302:isolation & purification / Q000378:metabolism; D013430:Sulfate Adenylyltransferase / Q000302:isolation & purification / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D016999:Sulfur-Reducing Bacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D013431:Sulfates; D050862:Oxidoreductases Acting on Sulfur Group Donors; C019618:adenylylsulfate reductase; D050885:Hydrogensulfite Reductase; D013430:Sulfate Adenylyltransferase; D008697:Methane